1. Field of the Invention
This invention relates to a composite sliding surface bearing comprising a load-carrying backing shell, a bearing metal layer applied to the inside surface of the backing shell, an interlayer provided on the inside surface of the bearing metal layer, and a sliding surface layer provided on the inside surface of the interlayer.
2. Description of the Prior Art
So-called composite or laminated bearings have been provided to resist the dynamic and thermal loads to which high-duty bearings are subjected. An interlayer is provided between a relatively soft sliding surface layer and a relatively hard bearing metal layer. Such interlayers constitute diffusion barriers if they are associated with copper-containing sliding surface layers, or bonding layers if they are associated with sliding surface layers consisting of light alloys. Such interlayer usually consists of nickel and is much harder than the sliding surface layer so that a wear of the softer sliding surface layer will greatly increase the risk of a local overloading by disturbing influences because the interlayer will be effective on a larger proportion of the area of the sliding surface after such wear has occurred. Because the sliding surface layer should have a high surface finish, the bearing metal layer and the interlayer are also made to have a relatively small peak-to-valley height so that a wear of the sliding surface layer will result in a breakthrough of the interlayer over an area. For this reason it has been attempted to make the interlayer as thin as possible in order to promote a rapid wear of the interlayer. Whereas that step will promote the life of the bearing, it has the result that the diffusion barrier or bonding functions of the interlayer are eliminated in part. Besides, the application of a very thin interlayer can be effected only in a special process, which adds to the costs of manufacturing such bearings.